The monitoring of movements of monitored individuals involves a variety of sectors, including parolees and home confinement. The technology has its roots in the home arrest systems of the 1980's, in which a user wearable component—typically a “beacon” anklet that was locked to the monitored person—would communicate wirelessly with a stationary base unit. The range was limited to a few feet of the radio frequency transmitter and receiver. The base unit included a telephone connection for communicating with the authorities. If the monitored person left the short range allowed by the equipment, the tag and the base unit would lose contact and the base unit would respond by sending an alert to the authorities.
A later generation of the technology incorporated GPS and cellular telephone technology in a locked anklet. The device would actively record the location of the monitored person over time and transmit the data to a central monitoring location (e.g., police or parole monitoring services). The central location could store and analyze the data for prohibited movements (e.g., a sex offender near a school) or cross reference the movement data with crime data to see if the monitored person was near the crime at the time of the crime. U.S. Pat. Nos. 5,867,103, 6,160,481, 6,218,945, 6,512,456 and 6,703,936, incorporated herein by reference in their entireties, are each exemplary of such a system. The technology is also used to monitor other personal sectors (e.g., patients, children) and objects (e.g., cars, cargo).
The modern monitoring device includes a GPS receiver that determines location, a memory that stores location data over time to define a movement history, and a cellular modem that communicates the movement history to a central location through the cell network. A common implementation is in the criminal justice system as an alternative to incarceration, and monitored persons (typically parolees) have tamper resistant devices attached to their leg or wrist.
Various attempts have been made to circumvent the monitoring devices via an external modification to prevent receipt of GPS signals and/or transmission of the movement data. Examples of such attempts include wrapping the monitoring device in foil or generating a local jamming signal.
An area in which monitoring devices have historically been immune to interference is hacking into the data transmission of the device itself. The tracking devices include various tamper detection methodologies, such that any attempt to breach the shell of the monitoring device and access the inner electronics would be detected (either electronically or by the visible physical damage to the casing). The cellular networks that the devices communicate with have historically been generally inaccessible to the public. Some monitoring devices also communicate locally (wifi range) with trusted dedicated receivers that also include various tamper detection methodologies, such that any attempt to breach the shell of the trusted dedicated receivers and access the inner electronics would be detected (either electronically or by the visible physical damage to the casing). Absent access to the internal electronics or cell network, the data stream from the monitoring devices is secure.
In recent years, various technologies have emerged that allow a greater degree of local access to cellular communications. For example, some telecommunication companies now provide cellular base stations that mimic a small cell tower and provide local cellular service through a high speed Internet connection; the Samsung SCS-26UC4 Verizon Network Extender Base Station is an example of such a device. Similar (in some cases illegal) technologies also allow users to construct their own local cellular base station through their laptop or PC. These devices have an open air range of several dozen yards, less so when in an enclosed building.
Monitoring devices tend to use standardized cellular modem technology that switch between cell towers as appropriate. Such devices under appropriate conditions could detach from the local cell tower and attach to a local legal/illegal short range cellular base station. Data flow from the monitoring devices would thus be passing through this local connection.